it is worth noting that (depending on the situation) it's actually better not to include variables inside strings in this way. if you do, the way daniel suggested is better - as he stated, it's easier to read.

note the use of single quotes instead of double. double quotes will have PHP do extra parsing. sure, the performance hit is nothing to cry about - but worth noting, nonetheless.
as for HEREDOC, i personally find it a bit clumsy for keeping things tidy and organised - but again, that is my own preference, not the norm.

Cheers
Mark

"you have to keep pissing in the wind to learn how to keep your shoes dry..."

Good advice redbullmarky, when the situation allows, I like your mentioned way as well. Looks nice and easy to debug as you mentioned. Both are nice, but the slightest bit of performance hit gives the way you mentioned the edge. Therefore I'll probably end up doing it that way. Ha, and to think, right after I got done going through a while script and doing it the other way, I learn a new way. Ah well. Thanks guys for all the advice.

I think the performance impact between single and double quoted strings is probably minimal at best and probably not worth worrying about in most cases. I do agree that leaving variables outside the strings makes them easier to find though.